You may have heard that cannabis lowers testosterone, there is a lot of talk about it these days. However, you may have noticed that cannabis has soared in popularity among those who work out regularly. So what gives?
Let’s begin looking at the testosterone issue by examining one of the things cannabis is so often accused of, Gynecomastia. Gynecomastia is the medical term for “man boobs”, and there is a lot of talk cannabis can cause it. Instead of speculating, let’s look at the science involved.
The question about cannabis and Gynecomastia dates back to the early seventies when a couple of case studies connected the two. It was suggested that cannabis is estrogenic and disrupts the hormonal balance in males.
In 2013, an article was published by CNN linking cannabis use as a plausible cause of “man boobs”. The article was endorsed by a cosmetic surgeon named Dr. Youn who greatly exaggerated the case for a “plausible link” – for someone who performs gynecomastia surgeries, obviously, there would be a link.
The CNN article is what spurred a range of rumors and speculations that remain today.
So where can we find the truth?
There is a test-tube study that shows compounds of cannabis to compete with estradiol (a major estrogen) for binding to estrogen receptors. However, when the same experiment was run using animal models, researchers found that there was neither an estrogenic nor anti-estrogenic effect. A cell-culture study on breast cancer cells also found no influence of cannabis on estrogen receptors.
But cell-culture and test-tube studies usually do not have an implication on humans.
The only human study available on gynecomastia and testosterone was performed in US army soldiers. The study reported no link between gynecomastia and cannabis consumption, but the sample size of 11 men is insignificant to draw any definitive conclusions.
Cannabis’s Affect On Testosterone – What The Research Says
The following are six human studies that observed the influence of cannabis on testosterone:
a) In men, an intravenous infusion of 10mg of THC – the active ingredient in cannabis – over 50 minutes showed a time-dependent decrease in testosterone. When compared to the control group, the subjects had 36% lower testosterone levels. In the same experiment, a separate group of subjects smoked a cannabis cigarette, after which their testosterone level dropped to 66% of their baseline value (1).
b) 4 healthy male volunteers were brought into a lab and assessed for hormonal concentrations before and after smoking cannabis cigarettes containing 2.8% THC. After smoking, a significant reduction in LH (a precursor for testosterone) was noted, while FSH (another precursor for T) and testosterone levels were only slightly supressed (2).
c) A study using isolated THC on 17 male volunteers over 4-days found no alteration in cortisol, LH, or testosterone levels (3).
d) Testosterone measurements were assessed in 25 male university students who regularly smoked cannabis (minimum of 1 time per week with an average of 5.1 joints per week). When compared to 13 non-smoking control subjects, the cannabis smokers’ testosterone levels were about the same (4).
e) 93 men and 56 women (average age=23.5) were brought into a lab and assessed for various hormonal parameters (LH, FSH, testosterone, cortisol, and prolactin). Subjects were grouped based on their frequency of cannabis use – frequent, moderate, and infrequent. When compared to the 75-non smoking control subjects, no significant differences in hormone concentrations were noted in either men or women across all groups (5).
f) 20 male subjects (aged 18-28) who smoked cannabis at least 4-days per week for a minimum of 6-months were brought into a lab. The average testosterone level in these subjects was 44% lower (416 ng/dL versus 742 ng/dL) compared to the control group who never used cannabis (6).
Of the six studies cited above, half show a decrease in testosterone after cannabis use, while the other three show no effect.
Keep in mind that your testosterone level is not just one number. Testosterone secretion fluctuates rapidly based on a number of factors like the time of day, whether you’ve eaten any food, whether you’ve worked out, how much sleep you got the previous night, etc. Smoking cannabis is just one of the many factors that may also have an influence.